An attorney adds a twist to his long, losing battle against a restrictive U.S. shipping law.

At 85, John Carroll, a Honolulu attorney, is nine years younger than the Jones Act, which he has spent much of his life trying to overturn. The act, passed in 1920, requires that goods transported between American ports be carried on U.S.-owned, U.S.-built ships, manned by U.S. crews. Carroll has mounted...